Stabilized microwave-frequency transfer using optical phase sensing and actuation

We present a stabilized microwave-frequency transfer technique that is based on optical phase-sensing and optical phase-actuation. This technique shares several attributes with optical-frequency transfer and therefore exhibits several advantages over other microwave-frequency transfer techniques. We demonstrated stabilized transfer of an 8,000 MHz microwave-frequency signal over a 166 km metropolitan optical fiber network, achieving a fractional frequency stability of 6.8x10^-14 Hz/Hz at 1 s integration, and 5.0x10^-16 Hz/Hz at 1.6x10^4 s. This technique is being considered for use on the Square Kilometre Array SKA1-mid radio telescope.